The objective of this study is to test the effectiveness of an evidence-based, Spanish language prescription drug (Rx) labeling strategy to improve patient understanding and use. The primary aims of this study are to: 1) Test the efficacy of enhanced Spanish Rx labeling (container label, leaflet) to improve Spanish-speaking patients' understanding of instructions compared to two current standard labeling strategies, and 2) Evaluate the effectiveness of the enhanced Rx labeling to improve Spanish-speaking patients' understanding and actual use of their own medicine compared to a current labeling standard. Research activities will be conducted in three phases: i) Preparation, ii) Comprehension Testing, and iii) Actual Use Assessment. During a brief Preparation phase, an evidence-based Spanish language Rx container label prototype and accompanying 'enhanced print' leaflets will be refined and pilot tested among Spanish-speaking adults recruited from three diverse settings. In the Comprehension Testing phase, Spanish-speaking patients' ability to comprehend the instructions for use on the enhanced Rx labeling will be compared against two standard labeling practices representing current pharmacy practices. For Aim 2, the proposed research study takes advantage of a rare opportunity within a pharmacy practice to evaluate the effectiveness of this evidence-based, Spanish Rx labeling strategy in actual use. A randomized trial will be conducted among diabetic Spanish-speaking patients at safety-net clinics affiliated with a central-fill pharmacy. Correct understanding and self-reported adherence (3-month follow-up) will be compared between Spanish-speaking patients who receive the enhanced Rx labeling and those receiving current standard labeling for all of their prescribed medicines. Pharmacy and medical records data will be used in exploratory analyses to examine label differences in adherence (refill), health care use, and outcome (HBA1C) at one year. We will also conduct a 'post-use' formative assessment of patients' perspectives regarding the clarity and utility of enhanced Rx labeling, and gather patient data pertaining to specific cultural factors to examine the association between health beliefs and practices on medication understanding and use. Findings gathered will inform anticipated next steps for a dissemination strategy.